What is the difference between "backstage" and "in the wings"?

For In the Wings “This expression alludes to the theater, where a player waits in the wings or backstage area, unseen by the audience, for his or her turn to come on stage.”

Backstage: “Areas of the theatre adjacent to the stage accessible only to performers and technicians, including the wings, crossover, and dressing rooms.”

So the difference is that they aren’t the same thing but together help the theatre work in sync

The answer to your question is a. true.